Antijackknife device



April 26, 1949. E. R. PRICE 2,468,705

ANTIJACKKNIFE DEVICE INVENI'OE fA/PL E P/F/CE ATTOfi/VEY April 26, 1949. pmc 2,468,705

ANTIJ'ACKKNIFE DEVICE Original Filed Aug. 11, 1944 2 Sheets-$heet 2 INVENTO)? *5/15; PE/CE ATTORNEY Patented Apr- 1949 ANTIJACKKNIFE DEVICE Earl R. Price, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, Imil, av corporation: ctv Delaware Continuation of application Serial No. 548398;.

August 11', 1944'. This application July 2, 1947', Serial No. 7581569 Claims. (01. 280-33105) l 2 This invention relates to tractor-trailer vetures of the present invention will become" a-p-- hicle' combinations. The primary object of the parent during the course of the followingdeinvention is to prevent j'ackknifing of such tracscription, reference being had therein to the ac'-- tor and trailer combinations; The'present applioompanying drawings, in which.

cation is a continuation of application Serial cal Figure l is a diagra-"mmatic'viewshowing my No. 548,998", filed August L1, 1944, now abandoned. invention applied to a tractor-trailer vehicle Jackknifing is the undesired swinging of combination;

either of the: tractor or trailer-to: one side of the Fiugre 2- is a close up of a portion of' the de-' proper line of motion of the vehicle train, the: vice shown in Figure 1; two vehicles closing: upon one another as the u.

Figure 3 is a perspective showing theupper and blades of a jackknife. It is most likely to occur lower fifth wheel plates and' the kingpin in locked when the trailer is1of thezsemi-trailer type; havrelationship with the lower fifth wheel plate; ing rear wheels only, and; supported at the front and by afifth Wheel'onthe-tractor. Figure 4 is a diagrammatic showing of a mod-- Jackknifing is almost invariably caused: by ified arrangement;

skidding of wheels on either the tractor'or trailer Referring to Figure 1, a tractor vehicle is or on both vehicles. As longv as the Wheels are shown at i2 and the front: end of a trailer verolling, the vehicles tend to: move in the proper" hicle is shown at. I4; In the illustrated arrangedirection, but when the wheels begin to slide, ment, the tractor has front wheels (not shown),

they can move aseasily in any other directionas i0 and rear wheels l5; and the trailer has rear they can movestrai-ght. ahead; Consequently, wheels only (not shown); The front end of the when a slight turning. or swinging, movement of trailer is supp on the real 0f the tractor one of the vehicles relative to the other occurs, ym n f the usual f hw r n n it is easy for such swingingmovementtovcontinue indicated generally at I81; Thestructure of the until the entire unit'isout ofcontrol; The far- 35 fifth wheel, y, 1m general, be Conventional;

ther out-of-line the: swing ng vehicle gets, the Th w r fif hwh l plate ;w i is s ppor harder it is to pull it back into line, since the foreon the tractor, is preferably mounted on the and-aft axis of its wheels is at a greater angle of oss Which permits movement of the inclination with respectto the direction: of: movcl wer fif h Whe l plate w n the vehicle train ment of the train, and its Wheels are therefore oves O r a pand: t inclination of One less likely toresume norma -Man n, vehicle momentarily changes withv respect to the Heretofore, the approach tothe jackknifing other. The upper fifth wheel plate=z4ris mounted problem has been toeither increase the effectiveon the trailer, and the shodp kingpin 26 ness of the trailer brakesor toprOVidemeans-fm" (See Figure 3) t nds from the ppe fi applying the trailer brak i kl ith t, th wheelplate' 24 into. an opening in the lower fifth usual time lag due to long connecting lines, Pr wheelplate 20, in whichit is locked. against either sumably, the theory has been. that, becaus aprelative upward or relativelengthwise movement parently the trailer usuallycauses jackknifing. by a spring loaded automatic. locking plate 2| reby running upon the tractor, the problem could tained in the lower filth wheel plate 2!), the

be solved. by havingthe trailer, during decelerakingpin serving totransmit themotive force betion, pulling. back on thetpactor, rather than. tween the tractor and trailer while serving as a. having thetractor pushing back on thetrailgr, pivot for relative turningmovement of the trac- To accomplish this seems a practical impossitor andtrailer. During. suchturningmovement. bility since the tractor brakes invariabl have. e pp fifth Wheel plateslides on the lower an eiiectiveness in excess. of that required. to fi e pla iemerely decelerate the relatively light tractor ve- The ucture thus. far described is convenhicle, and therefore the tractor brakes assist the tional- I propose to Provide, means for at times trailer brakes in stopping the trailer,. the tractor resis in r v turnin m v n b w the pushing back on the kingpin which connect tractor and trailer, in. order to-prevent jackknifthe vehicles. ing. The upper fifth. wheel plate 24 may be pro. I propose to provide. means which: act directly vided with an opening. or depression 21 (see and positively to prevent or restrict undesired closeup in- Figure 2). The lower fifth wheel turning or swinging movement of one of the ve-- plate 231 may support a plunger orlatch 2-8 adapt-- hicles relative to the other (-i-.. e jachlmifing). ed at. times to move intotheopening 21 and Other obiects-,.advantages-,iand important iea- .35 thereby resist turning of the" upper and lower fifth wheel plates relative to one another. In the drawings, the plunger 28 is shown reciprocable in a tube 30 depending from the lower fifth wheel plate. The means for moving the plunger may comprise a lever 32 pivoted at 34 and having a portion 38 engaging the lower end of the plunger, and a rod 38 pivotally connected to the lever 32 at 40, and adapted to be actuated by the pressure responsive member (piston or diaphragm) of a power device 42. The power device 52 may be supported on a bracket M, which in turn may be mounted on a flange 46 of the lower fifth wheel plate. In place of power device 42, a direct manual control for the plunger 28 might be provided.

Control of the power device 42 may be accomplished in any desired manner. In the illustrated device, a solenoid valve is used. This valve is illustrated in outline at 48, 'anud comprises a valve member which either connects or disconnects the left side of power device 42 from a pipe 58 leading to a positive or negative pressure source, such as the usual intake manifold, which develops a vacuum. The valve member of the solenoid valve is controlled by the usual solenoid armature, which in turn is regulated by a coil in an electric circuit. The electric circuit, in addition to the solenoid, may include a manually operable switch 52 and an automatically operable switch. such as the stoplight switch 54.

The tractor l2 has the usual brake operating system, which may include a master cylinder 56 connected to the brakes by conduit 58, and actuated by a pedal 60. The tractor also has the usual steering mechanism controlled by a steering wheel 62.

Operation of the device for preventing jackknifing is as follows. Assuming the manually operable switch 52 is closed, actuation of the brakes completes the electric circuit by closing the stoplight switch 54. The solenoid is energized to move the solenoid armature and thereby permit communication, heretofore prevented, between the vacuum source and the left end of power device 42. This draws the rod 38 to the left, exerting a force tending to move the lever 32 and plunger 28 into the dotted line position shown in Figure 2. Assuming the plunger 28 is in alignment with opening 21, it will be free to move into the dotted line position shown. The arrangement is such that the plunger is aligned with the opening when the tractor and trailer are in a substantially straight line. The angle through which one of the vehicles would have to move away from the straight line position in order to prevent engagement of the plunger 28 in the opening 2'! is a matter of choice. Preferably, at least a few degrees of latitude are allowed.

In the engaged position, the plunger 28 tends to prevent relative rotation of the upper and lower fifth wheel plates, and thereby tends to prevent relative turning movement of the tractor and trailer about the kingpin 25. Thus any tendency of the vehicle to jackknife is opposed-by positively acting means which acts in a direct way to prevent the relative swinging movement associated with jacknifing.

It is not intended that the plunger 28 lock the fifth wheel plates together with such force that they cannot move relatively to one another when the operator wishes to turn the vehicle train. To this end I have provided complementary tapering surfaces on the inside of opening 21 and on the upper end 54 of the plunger 28, in order that the surface of opening 21 may act as a cam in forcing plunger 28 out of engagement when sufiicient force is developed.

The force holding plunger 28 in engagement with the upper fifth wheel plate will depend upon several things, among them the pressure exerted by the device 42, the leverage ratio of the mechanism between the power device and the plunger, the angle of taper of the surfaces 64 and 21, and the lever arm or radial distance between the opening 27 and the kingpin 26. 'lhe arrangement must, of course, be such that force created by turning the steering mechanism of the tractor will overcome the force tending to hold plunger 28 in engaged position, and will move the plunger downwardly to permit relative turning movement of the upper and lower fifth wheel plates. The force against the plunger created by turning the steering mechanism of the tractor is large, and is much greater than that required to prevent jackknifing.

This is true because any tendency of the vehicles to jackknife is relatively weak so long as the angle of movement is slight. By exerting a force tending to hold the tractor and trailer in a straight line, and thus guarding against the beginning of jackknife, the tendency can be effectively overcome. By preventing the jackknifing or turning at the start, I can accomplish with a relatively small force a result which would be almost impossible to accomplish at a later point in the jackknife.

It is true that the anti-jacknife device will not operate if the vehicle train is turning through a substantial angle at the time the brakes are applied. However, the danger of driving on a curving road which is wet or icy is an obvious one and one which the driver must compensate for. The unexpected, and therefore most treacherous,

jackknife occurs when the vehicles are moving in.

a substantially straight line, and the driver, in view of this, has developed a fairly high speed. It will be noted that the tapered arrangement of the plunger is such as to tend to center the trailer even though it may have moved a few degrees to one side or the other, but not enough to prevent the tip of the plunger from entering the large end of the opening in the upper fifth wheel plate.

Figure 4 shows a modified arrangement in which a device is used to clamp the upper and lower fifth wheel plates together, and thereby resist relative rotation of the plates. The device, which is shown diagrammatically, may comprise an arm 66 secured to the lower fifth wheel plate 20, and a lever 68 pivoted at 10 on the arm 66 and having a portion 12 adapted to exert a downward force on the upper fifth wheel plate 24 tending to clamp the plates together. The lever 68 may be operated by any desired means. It may be controlled by direct manual application, or it may be controlled by a power device M, as shown. The power device M may in turn be controlled manually, or may be caused to operate automatically whenever the brakes are applied, as in the preceding embodiment. The operation of this device is generally similar to that of the preceding embodiment, except that the friction creating force takes the place of the force exerted on the plunger or latch.

Although particular embodiments of my invention have been described, it will be understood by those skilled in the art that the object of the invention may be attained by the use of constructions different in certain respects from those disclosed without departing from the underlying principles of the invention. I therefore desire by the following claims to include within the scope or my invention all such variations and modifications by which substantially the results of my invention :may :be obtained through the use "0*! substantially the same or equivalent .means.

I claim:

l. For use in a tractor-trailer vehicle combination having steering mechanism on the tractor, a :kinglpin transmitting motive force from the tractor -to the trailer and serving as :a pivot .ior .rela'tive turning movement of the tractor and trailer, an npperfiith wheel on'the trailer hailing an opening therein, and a lower Jfifth wheel on :the tractor (ODBIElSlVfilY associated with the upper fifth wheel and having :an opening tlierethrough 'aligned'with the opening in the upper fifth wheel when the tractor and trailer .are "in a substantial :ly straight line; .a device for preventing jackiknifin'g of the tractor-trailer vehicle combination -comprising a plunger normally extending into the opening in the lower fifth wheel but not into the opening in :the upper fifth wheel, and means tor :moving :said plunger into the opening in the upper =fiifthwheel'to'resist relative turning movement :of the upper "and flower fifth wheels and thereby resist relative turning movement of the tractor and trailer, the bottom surface of the opening in theupper fifth wheel being formed to :act as a cam in 'order that force tending to cause relative turning movement of the tractor and :trailer whenever the steering mechanism of the tractor 'is operated to select a difierent direction of movement may force the plunger-ou tof engagement with the upper fifth wheel.

.2. In a tractor-trailervehiclecombination hav- :a

ing brakes, 1a kingpin transmitting motive force from the tractor to the trailer and serving as a pivot for relative turning movement of the tram tor and trailer, an upper fifth wheel plate "on the trailer having an opening spaced from the king- .pin a predetermined radial distance, and a lower fifth wheel platoon the tractor in engagement with the upper fiifth wheel plate, means for preventing jackknifing ot the tractor-trailer vehicle combination comprising a plunger mounted'in the :lower fifth wheel plate and in alignment with "the opening in the upper Jfifth wheel plate when the tractor and trailer are in a straight line or within a :few :degrees thereof, mechanism for exerting a :force on said "plunger to move it into opening in the upper :fifth Wheel plate to thereby resist relative turning movement of the tractor and trailer about the iking-pin pivot, a power device "operating said mechanism, valve means controlling said :POWEI device, and means regulating said valve means to cause :the plunger to tend to move into the opening in the upper fifth wheel plate whenever the tractor-trailer brakes are applied, the inner surface :of the opening in the upper fifth wheel :plate and the end surface of the plunger being tapered to permit the tractor steering mechanism to override the jackknife pre venting .means and force the plunger out of engagement with the upper fifth wheel plate whenever the operator desires to turn the tractor and trailer.

3. Foruse in a tractor-trailer combination having aneoper-ator operated brakecontrol member on the tractor, and relatively rotatable elements associated respectively with the trailer and "the tractor; means for preventing jackknifing of the trailer comprising a conical opening formed in the element associated with the trailer, a plunger guided by the element associated with the tractor and movable longitudinally toward or away from the "aforementioned conical opening, said plunger being aligned with said conical opening when the tractor and trailer are moving in the same direction, said plunger having a conical end portion adapted to enter said opening and thereby resist relative rotational movement of said relatively rotatable elements, thus tending to hold the tractor and trailer in a straight-line relationship, the conical shape of the plunger end and of the opening serving both to enable the plunger to enter the opening in spite of slight misalignment and also to permit an unusually strong force to overrule the locking effect of the plunger and force it-outxof the opening, a lever acti'ngon said plunger, a power cylinder havinga pressure responsive movable element which actuatcs said lever, valve means controlling said power cylinder, electro magnetic means arranged to operate said valve means, and an electrical circuit controlling said electromagnetic means including a switch actuated by the operator operated brake control memher.

4. For use inza tractor-trailer combination having an operator operated brake control member on the tractor, and relatively rotatable elements associated respectively with the trailer and the tractor, the upper of said elements being associated with the trailer and the lower of said ele-- ments being associated with the tractor; means for preventing jackknifing of the trailer comprising a conical opening formed in the element associated with the trailena vertically :movabl'e'plunger guided by the element associated with the tractor and movable toward or away from the aforementioned conical opening, said plunger being aligned with said conical opening when the tractor and trailer are moving in the same direction, said plunger having a :conical end portion adapted to enter said opening and thereby resist relative rotational movement of said relatively rotatable elements, thus tending to hold the tractor and trailer in a straight-line relationship, the conical shape of the plu'nger end and :of the opening serving both to enable the plunger to enter the opening in spite :of slight misalignment "and also to permit an unusually strong force to overrule "the looking effect of the plunger and force it out of the opening, a lever adapted to lift the plunger into engagement with the conical opening, a pow-- er cylinder having a pressure responsive movable element which actuates said lever, valve means controlling said power cylinder, electromagnetic means arranged to operate said valve means, and an electrical circuit controlling said electromag netic means including a switch actuated by the operator operated brake control member.

5.. For use in :a tractor-trailer combination having an operator operated brake control member on the tractor, and relatively rotatable elements associated respectively with the traileran'dthe tractor; means for preventing iackknifing of the trailer comprising a conical opening formed in the clement-associated with the trailer, a -plunger guided by the element associated with the tractor and movable longitudinally toward or away from the aforementioned conical opening, said plunger ibeing aligned with :said conical opening when the tractor and trailer are :moving in the same direction, said plunger having :a conical lend portion adapted to enter said (opening and there-by resist relative rotational movement of said relatively rotatable elements, thus tending to hold the tractor and trailer in a straight-line relationship, the conical shape of the plunger end and of the opening serving both to enable the plunger to enter the opening in spite of slight misalignment and also to permit an unusually strong force to overrule the locking eifect of the plunger and force it out of the opening, and means under the control of the operator operated brake control member for actuating the plunger to cause its engagement with the conical opening.

6. For use in a tractor-trailer combination having an operator operated brake control member on the tractor, and relatively rotatable elements associated respectively with the trailer and the tractor; means for preventing jackknifin of the trailer comprising a conical opening formed in the element associated with the trailer, a plunger guided by the element associated with the tractor and movable longitudinally toward or away from the aforementioned conical opening, said plunger being aligned with said conical opening when the tractor and trailer are moving in the same direction, said plunger having a conical end portion adapted to enter said opening and thereby resist relative rotational movement of said relatively rotatable elements, thus tending to hold the tractor and trailer in a straight-line relationship, the conical shape of the plunger end and of the opening serving both to enable the plunger to enter the opening in spite of slight misalignment and also to permit an unusually strong force to overrule the locking effect of the plunger and force it out of the opening, a power cylinder having a pressure responsive movable element which actuates said plunger, valve means controlling said power cylinder, electromagnetic means arranged to operate said valve means, and an electrical circuit controlling said electromagnetic means including a switch actuated by the operator operated brake control member.

7. For use in a tractor-trailer combination having an operator operated brake control member on the tractor, and relatively rotatable elements associated respectively with the trailer and the tractor; means for preventing jackknifing of the trailer comprising an opening formed in the element associated with the trailer, a plunger guided by the element associated with the tractor and movable longitudinally into or out of the aforementioned opening, said plunger being aligned with said opening when the tractor and trailer are moving in the same direction, said plunger having an end portion adapted to enter said opening and thereby resist relative rotational movement of said relatively rotatable elements, thus tending to hold the tractor and trailer in a straight-line relationship, a power cylinder having a pressure responsive movable element which actuates said plunger, valve means controlling said power cylinder, electromagnetic means arranged to operate said Valve means, and an electrical circuit controlling said electromagnetic means including a switch actuated by the operator operated brake control member.

8. For use in a tractor-trailer combination having an operator operated brake control member on the tractor, and relatively rotatable elements associated respectively with the trailer and the tractor; means for preventing jackknifing of the trailer comprising a conical opening formed in the element associated with the trailer, and a plunger guided by the element associated with the tractor and movable longitudinally toward or away from the aforementioned conical opening, said plunger being aligned with said conical opening when the tractor and trailer are moving in the same direction, said plunger having a conical end portion adapted to enter said openingand thereby resist relative rotational movement of said relatively rotatable elements, thus tending to hold the tractor and trailer in a straight-line relationship, the conical shape of the plunger end and of the opening serving both to enable the plunger to enter the opening in spite of slight misalignment and also to permit an unusually strong force to overrule the locking effect of the plunger and force it out of the opening.

9. For use in a tractor-trailer vehicle combination having steering mechanism on the tractor, a pivotal connecting member transmitting motive force from the tractor'to the trailer and serving as a pivot for relative turning movement of the tractor and trailer, an upper fifth wheel on the trailer, and a lower fifth wheel on the tractor operatively associated with the upper fifth wheel; a device for preventing jackknifing of the tractortrailer vehicle combination comprising a plunger carried by one of said fifth wheels, the other of said fifth wheels having an opening therein which is aligned with said plunger when the tractor and trailer are in a substantially straight line, and means for moving said plunger into said opening to resist relative turning movement of the upper and lower fifth wheels and thereby resist relative turning movement of the tractor and trailer, the inner surface of said opening being formed to act as a cam in order that force tending to cause relative turning movement of the tractor and trailer whenever the steering mechanism of the tractor is operated to select a different direction of movement may force the plunger out of engagement with the fifth wheel having the opening.

10. For use in a tractor-trailer vehicle combination having steering mechanism on the tractor, and a pivotal connecting member transmit ting motive force from the tractor to the trailer and serving as a pivot for relative turning move ment of the tractor and trailer; a device for preventing jackknifing of the tractor-trailer vehicle combination comprising a plunger carried by one of said vehicles, the other of said Vehicles having a member provided with an opening which is aligned with said plunger when the tractor and trailer are in a substantially straight line, and means for moving said plunger into said opening to resist relative turning movement of the tractor and trailer, the inner surface of said opening being formed to act as a cam in order that force tending to cause relative turning movement of the tractor and trailer whenever the steering mechanism of the tractor is operated to select a different direction of movement may force the plunger out of engagement with said opening.

EARL R. PRICE.

REFERENCES CITED The following references are of record in the file of this patent: Q

UNITED STATES PATENTS Number Name Date 1,374,352 Borst Apr, 12, 1921 2,188,727 Soulis Jan. 30, 1940 2,213,221 Johnson Sept. 3, 1940 

